feat: add ZynML VS Code syntax highlighting extension

Adds a local VS Code extension for ZynML syntax highlighting:
- TextMate grammar for .zynml and .zyn files
- Keywords: def, fn, struct, enum, trait, impl, effect, handler
- Control flow: if, else, elif, match, case, for, while, async, await
- Type highlighting: primitives, built-ins, generics
- Operators: |>, =>, ->, ??, ?, ::
- Annotations: @effect, @device, @jit
- F-string interpolation support
- Number literals with suffixes (duration, etc.)
- Language configuration for brackets, comments, indentation

Installed via symlink to ~/.vscode/extensions/

Author: darmie

.vscode/extensions.json

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+{
+  "recommendations": [
+    "zyntax.zynml-syntax"
+  ]
+}

.vscode/extensions/zynml-syntax/CHANGELOG.md

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+# Changelog
+
+## [0.1.0] - 2026-01-17
+
+### Added
+
+- Initial release of ZynML syntax highlighting
+- Support for `.zynml` and `.zyn` file extensions
+- Syntax highlighting for:
+  - Keywords: `def`, `fn`, `struct`, `enum`, `trait`, `impl`, `type`, `let`, `mut`
+  - Control flow: `if`, `else`, `elif`, `match`, `case`, `for`, `while`, `return`
+  - Async: `async`, `await`
+  - Effects: `effect`, `handler`, `where`
+  - Primitive types: `i64`, `f64`, `bool`, `str`, `String`
+  - Built-in types: `Option`, `Result`, `List`, `HashMap`, `Tensor`, `Iterator`
+  - Operators: `|>`, `=>`, `->`, `??`, `?`, `::`
+  - Annotations: `@effect`, `@device`, `@jit`
+  - String literals and f-strings with interpolation
+  - Numbers with suffixes (duration literals, etc.)
+  - Comments (line and block)
+- Language configuration for:
+  - Bracket matching
+  - Auto-closing pairs
+  - Comment toggling
+  - Indentation rules

.vscode/extensions/zynml-syntax/README.md

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+# ZynML Language Support
+
+Syntax highlighting for ZynML - the Machine Learning DSL for Zyntax.
+
+## Features
+
+- Syntax highlighting for `.zynml` and `.zyn` files
+- Bracket matching and auto-closing
+- Comment toggling (`//` and `/* */`)
+- Code folding
+
+## Highlighted Constructs
+
+### Keywords
+- Control flow: `if`, `else`, `elif`, `match`, `case`, `for`, `while`, `return`
+- Declarations: `def`, `fn`, `struct`, `enum`, `trait`, `impl`, `type`, `let`, `mut`
+- Async: `async`, `await`
+- Effects: `effect`, `handler`, `where`
+
+### Types
+- Primitives: `i64`, `f64`, `bool`, `str`, `String`
+- Built-ins: `Option`, `Result`, `List`, `HashMap`, `Tensor`, `Iterator`
+- Type variables (capitalized identifiers)
+
+### Literals
+- Numbers with optional suffixes: `1000ms`, `5s`, `3.14`
+- Strings and f-strings: `"hello"`, `f"Hello {name}"`
+- Booleans: `true`, `false`
+- Option/Result: `Some`, `None`, `Ok`, `Err`
+
+### Operators
+- Pipe: `|>`
+- Arrows: `=>`, `->`, `:`
+- Null coalesce: `??`
+- Optional: `?`
+- Path: `::`
+
+### Annotations
+- `@effect(IO)`
+- `@device(GPU(0))`
+- `@jit`
+
+## Installation
+
+### Local Development
+
+1. Copy or symlink this folder to your VS Code extensions directory:
+   - macOS/Linux: `~/.vscode/extensions/`
+   - Windows: `%USERPROFILE%\.vscode\extensions\`
+
+2. Reload VS Code
+
+### From Workspace
+
+Add to your `.vscode/settings.json`:
+
+```json
+{
+  "files.associations": {
+    "*.zynml": "zynml",
+    "*.zyn": "zynml"
+  }
+}
+```
+
+## Example
+
+```zynml
+// Define a struct with generics
+struct Point<T> {
+    x: T,
+    y: T
+}
+
+// Implement Display trait
+impl<T> Display for Point<T>
+    where T: Display
+{
+    def to_string(self): String {
+        f"({self.x}, {self.y})"
+    }
+}
+
+// Function with pattern matching
+def process(data: List<i64>): ?i64 {
+    match data.first() {
+        case Some(v) { Some(v * 2) }
+        case None() { None }
+    }
+}
+
+// Async function with effect
+@effect(IO)
+async def fetch_and_process(url: String): Tensor {
+    data = await http.get(url)
+    data |> parse() |> normalize() |> transform()
+}
+```
+
+## License
+
+Apache-2.0

.vscode/extensions/zynml-syntax/language-configuration.json

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+{
+  "comments": {
+    "lineComment": "//",
+    "blockComment": ["/*", "*/"]
+  },
+  "brackets": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"],
+    ["<", ">"]
+  ],
+  "autoClosingPairs": [
+    { "open": "{", "close": "}" },
+    { "open": "[", "close": "]" },
+    { "open": "(", "close": ")" },
+    { "open": "<", "close": ">", "notIn": ["string"] },
+    { "open": "\"", "close": "\"", "notIn": ["string"] },
+    { "open": "'", "close": "'", "notIn": ["string", "comment"] }
+  ],
+  "surroundingPairs": [
+    { "open": "{", "close": "}" },
+    { "open": "[", "close": "]" },
+    { "open": "(", "close": ")" },
+    { "open": "<", "close": ">" },
+    { "open": "\"", "close": "\"" },
+    { "open": "'", "close": "'" }
+  ],
+  "folding": {
+    "markers": {
+      "start": "^\\s*//\\s*region\\b",
+      "end": "^\\s*//\\s*endregion\\b"
+    }
+  },
+  "indentationRules": {
+    "increaseIndentPattern": "^.*\\{[^}\"']*$|^.*\\([^)\"']*$|^.*\\[[^\\]\"']*$",
+    "decreaseIndentPattern": "^\\s*[}\\]\\)]"
+  },
+  "wordPattern": "[a-zA-Z_][a-zA-Z0-9_]*"
+}

.vscode/extensions/zynml-syntax/package.json

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+{
+  "name": "zynml-syntax",
+  "displayName": "ZynML Language Support",
+  "description": "Syntax highlighting for ZynML - Machine Learning DSL for Zyntax",
+  "version": "0.1.0",
+  "publisher": "zyntax",
+  "engines": {
+    "vscode": "^1.75.0"
+  },
+  "categories": [
+    "Programming Languages"
+  ],
+  "contributes": {
+    "languages": [
+      {
+        "id": "zynml",
+        "aliases": ["ZynML", "zynml"],
+        "extensions": [".zynml", ".zyn"],
+        "configuration": "./language-configuration.json"
+      }
+    ],
+    "grammars": [
+      {
+        "language": "zynml",
+        "scopeName": "source.zynml",
+        "path": "./syntaxes/zynml.tmLanguage.json"
+      }
+    ]
+  }
+}